Those who do not study history... Back in the early 1930's the German railways compared four different power transmission methods in four locomotives powered by identical diesel engines. The diesel mechanical was poor. The diesel hydraulic didn't turn them on. Diesel electric worked well. The best, clearly, was a diesel-pneumatic locomotive, more fuel-efficient and faster. What worked well then would work well now, especially as a hybrid, storing energy in compressed air tanks (simple ferrous metal or composite technology) instead of expensive batteries. (see US patent 5,832,728) The diesel engine drives an air pump, which could be interal with the engine, and the air supplies a "steam engine" (the drive motor). (the Germans converted a steam locomotive) There are two tricks which make it practical:

(1) Cool the pump by injecting water, so the output is a mixture of air and steam. As the air expands, doing work, the steam condenses, and the latent heat reheats the air. It thermodynamically efficient: cool air and water in, cool air and water out, little wasted heat. (Filter out the water droplets and you can drink them or recycle them)

(2) Use waste heat from the diesel exhaust to heat the pump output, getting "something for nothing."

In the modern context, add some storage tanks. (At 30 bar, 300C, you can store about a kilowatt-hour per cubic foot) For regenerative braking, use "engine braking" where the pump is driven by the vehicle momentum and puts the output into a tank instead of the drive motor.

There are no scarce or toxic materials involved, and the technology is simple and mature. Hitler wanted the fuel for tanks and planes, so the German railroads scrapped their diesels, but what they could do in 1932 should be easy 80 years later and applicable to automobiles. If I had the money, I'd convert a diesel truck, putting enough scuba tanks in or under the bed to have a pollution-free range of 100 miles on stored air. With the tanks full, I could drag race Corvettes.

Charles, I'm not sure it's taxes ... they tend to be not a significant factor, even with a bias to try and balance road repair based on typical vehicle axle weights between the two fuels. I think it's more the strong environmentalist dislike for "dirty diesel" because of visible exhaust particulates on smell differences.

Cost of fuel is a small factor, in that we have gone thru several reductions of sulfur, that have caused higher diesel prices as forumations changed. But in general, fuel economy differences, mitigate most of that higher per gallon sticker shock.

My ex-wife got upset when the sulfur content was dropped 15 years ago, and diesel prices spiked for a while. She asked that her 1982 2WD 6.2L suburban (averaging 20mpg) be replaced with a gas 1994 350 model (averaging 15mpg) ... and was suprised when her weekly fuel costs jumped 20% because of relatively poor fuel economy.

Being rural, we stack up quite a few more miles per year, in the 30-50K/yr range, so diesels tend to save about $3k/yr in fuel costs. We also tend to run our trucks to 500K miles over their lifetime (one of two new engines), so that savings in fuel cost exceeds the purchase price of the truck.

So far we have taken a 1963 corvair, a 1982 6.2L Suburban, a 1985 C3500 6.2L dually, a 1985 1/2ton stepside pickup over 500K miles ... and a couple others well over 300K miles. The 2001 TDI Beetle is now over 300K with a new enginee. My 1997 K2500 6.5L Suburban is my shop at 300K now, for a new engine and trans, and is likely to be the next to go over 500K inside the next 10 years.

Diesel is just cheaper to operate ... both in fuel cost, and repairs. That adds up significantly, to cover the entire purchase cost of a car/truck if operated over 300K miles.

Charles, my concern over 54.5 fleet MPG remains ... and your selection of examples is pretty clear. the only car close to that, is the sub compact at 40mpg. We still seem headed to the previous CAFE results where huge numbers of cars will be produced that lack critical crumple zones to ride down crashes with stationary objects that kill and severely injure the driver and passengers. This will raise cost of insurance in the long run, increasing cost of ownership.

All of these engines have significantly higher complexity, which frequently translates to significantly higher initial purchase costs, as well as increased lifetime maintenence costs, raising cost of ownership significantly.

Minimum wage is unlikely to increase as fast, so the poor people will see a higher portion of their income moved to transportation, both cost of ownership and fuel cost, while accident rates increase.

Overall, this will drive inflation in our economy to meet a politically motivated goal of removing automobiles from our society.

Charles, all the parts are not even 20% more costly, other than the significantly lower production volume problem which transfer higher NRE costs to each unit, for design, prototyping, tooling, testings, certification, ... etc. Certainly the materials are not 2X in cost, or they would be 2x beefier. It's really hard to see that looking at a VW 1.9L TDI diesel from 10 years ago. Other than slightly larger bearings, it's pretty much scaled to a 1.9L gas engine. With significantly higher fuel economy.

Or for that matter a GM 6.5L diesel from 10 years ago, compared to the 350 and 454 derivative designs that it competes with, where it's towing performance is between the two, and significantly better fuel economy than either.

I live in Europe and have a diesel-engine vehicle, and I don't know for sure if this is true but it makes sense, as it's less expensive than gasoline here. Overall, most people here prefer to have a diesel engine over a gasoline-powered one.

That would be quite a feat! As with so many other technologies, I am surprised it too so long for this to evolve, as even when I was young oh so many years ago, people were talking about electric cars...but they didn't really start manufacturing them until 20 years later. Lack of interest and investment then, of course. Now it's practically necessary to go in this direction.

I never thought car powertrain technology could be so interesting, being someone who is not savvy about cars in the slightest, but your slideshow was enlightening, Charles. It's nice to see what's being done to create more fuel efficiency. It is sorely needed!

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